Inventor's Summation
The following is a summation of the invention by the inventor.
"A commonly used method of separation and collecting particulate matter from the contaminated gases discharged from the stacks of power-plants and other industrial equipment is to direct the gas stream through the precipitator and by exposure to electrical energy to ionize the particulate matter suspended in the gas stream so that it is later attracted to the grounded elements known as collecting electrodes or plates. At certain time intervals the plates are vibrated (rapped) by mechanical means and the collected dust is dislodged and falls into hoppers. Discharge electrodes are also rapped and are suspended in conventional manner.
An undesirable outcome with the conventional collecting plate is that the particulate is mainly collected in the "quiescent zones" near the plate baffles for a short distance downstream. However, charged particles are also attracted to the flat surfaces of the plate between baffles on plates that are parallel with the gas flow. The passage of gases adjacent to these flat surfaces will cause the gas to pick up some of the collected dust on the plate and become recontaminated. This is known as particle re-entrainment and it is to be expected that further gas passage through the precipitator will, little by little, eventually re-collect some of the re-entrainment. This requires careful and meticulous adjustment of rapping intensity and frequencies and cycle timing because excessive rapping can aggravate the problem of re-entrainment.
A further disadvantage of the present parallel flow conventional designs is that the ionized particulate must "migrate" sideways across the flow of gas in which the particulate is suspended in order to reach the surfaces of the grounded collecting plate. The time it takes and the path it follows are influenced by the width of the gas lane and the momentum of the moving particle and the polarity pull from the grounded collecting plate. The resulting path is in the form of a trajectory, because the line of motion of the moving particle in the gas stream and the line of "polarity pull" from the collecting plate are 90.degree. apart. So there is time lapse and distance traveled before the particle is finally attached to the collecting plate. This trajectory distance represents loss of collectibility at each vertical edge of the plate.
Regardless of the many baffle designs in the parallel flow principle, such as triangular, "V" pockets, offset, shielded, etc. they cannot escape the detriment of longer migratory trajectories and in many cases high re-entrainment within the area of flat surfaces of the collecting plates where scrubbing takes place as the gases pick-up collected particulate from the plates when rapping occurs.
My invention provides for high conversion collecting zones that function alternately, for example, first on the right side of a split gas stream and then on the left side of the split gas stream, thus increasing the depth of collection or penetration into the gas stream. Particulate fall-out quiescent zones are also provided of greater volume than on conventional ESP's (electrostatic precipitators).
To quote from a paper delivered to the U.S. Environmental Protection Agency on May, 1980 by Jack McDonald and Alan Dean of the Southern Research Institute, page 22:
"Recent studies have been made to determine the effect of particle re-entrainment on precipitator performance. In studies where the rappers were not employed, real-time measurements of outlet emmisions at some installations showed that significant re-entrainment of mass was occurring due to factors other than rapping. These studies also showed that for high-efficiency full scale precipitators approximately 30-85% of the outlet particulate emissions could be attributed to rapper re-entrainment. The results of these studies show that particle re-entrainment is a significant factor in limiting precipitator performance."
It is with this background that my new "High Conversion Concept" is proposed with the belief that when re-entrainment has been reduced, the ultimate results can be smaller units, less ionization energy and less rapper energy with longer structural life of components, which will all contribute to the conservation of energy.